Protective device and signal means for circuit breakers



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Filed May 19 1944 A. e. STEINMAYER 2,468,645 PROTECTIVE DEVICE AND SIGNAL MEANS FOR CIRCUIT BREAKERS 9 Sheets-Sheet 4 ATTOPA/EV.

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PROTECTIVE DEVICE AND SIGNAL MEANS FOR CIRCUIT BREAKERS Filed May 19, 1944 9 Sheets-Sheet 5 j INVENTOR.

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Filed May 19, 1944 A. G. STEINMAYER 2,468,645 PROTECTIVE DEVICE AND SIGNAL MEANS FOR CIRCUIT BREAKERS 9 Sheets-Sheet 6 INVENTOR.

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' ing of this condition is given.

Patented Apr. 26, 1949 PROTECTIVE DEVICE AND SIGNAL MEANS FOR CIRCUIT BREAKERS Alwin G. Steinmayer, Milwaukee, Wis., assignor to Line Material Company, Milwaukee, Wis., a

corporation of Delaware Application May 19, 1944, Serial N0. 536,335

10 Claims. (Cl. 177-4311) This'invention relates to a switch construction.

In greater detail, this invention relates primarily to a switch construction of the circuit breaker type.

Objects of this invention are to provide a circuit breaker which has a quick make and a quick break, which has condition responsive means of the trip type, which is so constructed that it releases the circuit breaker so that the circuit breaker will open under predetermined conditions, and which is provided with a handle or other operating means for normally opening and closing the circuit breaker and for resetting the trip means, the trip means and the operating means being so related that the trip means will operate to release the circuit breaker irrespective of the position of the operating means and irrespective of any motion that the operating means may be executing at the time the trip means operates so that the trip means is trip free and will operate no matter whether the operating means is forcibly held in closed position or is being moved from one position to an other.

Further objects are to provide a circuit breaker which is so constructed that the circuit breaker cannot be closed until the trip means has moved back to normal position, and in which the resetting of the trip means is accomplished by moving the operating means towards open position, such motion being followed by movement to closed position after the resetting of the trip means when it is desired to again closethe clrcuit breaker after the occurrence of the predetermined condition. I

Transformers are frequently mounted in relatively remote locations and are not frequently inspected. It occasionally happens that a transformer is either permanently overloaded or else overloaded at certain periods and yet no warn- This invention has for a further object to provide a novel form of circuit breaker which may be mounted in a transformer casing and which in addition to the means adapted totrip the circuit breaker when an overload occurs is also provided with means adapted to give an indication or signal that the transformer is overloaded, though this overload may be to an extent not sufilcient to trip the circuit breaker, and which is so made that after the signal has been given, the signal will persist until the signal controlling means is reset so that it becomes an easy matter for a linemanto ascertain the condition of a transformer with- 2 out requiring him to conduct elaborate and extensive tests.

It is to be noted that frequently overloads occur which last through a prolonged period sufficient to heat the transformer to a material and undesirable degree and yet which are not suflicient to trip the circuit breaker. This invention, as stated hereinabove, provides means which will function independently of the circuit breaker tripping means and which means may be independently adjusted without changing the adjustment of the circuit breaker tripping means so that any desired spread between the response of the signal controlling means and the response of the circuit breaker tripping means may be secured, and to so construct the apparatus that the signal controlling means may be reset without opening the circuit breaker, and which is also so made that the circuit breaker cannot be reset without resetting the signal controlling means.

In greater detail, objects of this invention are to provide a circuit breaker adapted to be mounted within a transformer casing and provided with two distinctly separate thermostatically responsive means, one of which is adapted to trip the circuit breaker and the other of which is adapted to cause the closing of a signal switch, such, for example, as a light switch, and in which readily accessible means are provided for independently setting the adjustment of the thermostatic means for tripping the circuit breaker and the thermostatic means for closing the signal switch.

Further objects are to provide a circuit breaker construction which, as stated, may be installed within a transformer casing and may be mounted above or submerged in the oil in the transformer casing, is desired, and which may be arranged so that one or both of the thermostatic means responds solely to the heat generated by the current passing through the thermostatic means or to the combined action of the heat of the oil from the transformer as Well as the heat due to current passing through the thermostatic means or which may be arranged to respond solely to the heat of the oil.

Further objects are to provide a circuit breaker which has a heavy contact pressure when it is closed, in which this heavy contact pressure is maintained during the operation of the circuit breaker until the instant at which the contacts are suddenly separated, thereby avoiding burning of the contacts under overload conditions.

Further objects are to provide a circuit breaker in which the trip means is required to exert only a very small force in order to cause automatic operation, the relation of the parts insuring relatching without any chance of wedging or jamming either the trip mechanism as a whole or any portion of the latch means,

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a sectional elevation of the circuit breaker, such view corresponding to a section on the line 1-1 of Figure 2, and showing the circuit breaker in closed position.

Figure 2 is a sectional view on the line 2-2 of Figure 1 and on the line Z-2 of Figure 3.

Figure 3 is a sectional view on the line 3-3 of Figure 2.

Figure 4 is a sectional view on the line 4-4 of Figure 3.

Figure 5 is a sectional view on the line 5-4 of Figure 3.

Figure 6 is a sectional view corresponding to Figure 3 with some of the parts shown in full, such view showing the circuit breaker in manually open position.

Figure 7 is a view corresponding to Figure 3 showing some of the parts in full and showing the circuit breaker in automatically tripped position.

Figure 8 is atop plan view with the cover removed and with parts broken away.

Figure 9 is a fragmentary view showing the circuit breaker mounted in a transformer casing.

Figure 10 is a view taken on line 10-10 of Figure 9.

Figure 11 shows the circuit breaker positioned in a casing for wall mounting.

Figure 12 is a wiring diagram.

The circuit breaker comprises a base portion 1 formed of insulating material and provided with a raised, centrally located portion 2 which has an upwardly extending, integral projecting part or stop member 3. A top portion 4 is also formed of insulating material and is spaced upwardly from the base portion. The top is provided with a pair of downwardly extending integral leg portions 5 which fit within recesses 6 formed in the base. The legs 5 are joined by an integral transverse web or bar 1. A cover 8 is provided above the top portion 4 and is suitably seated in a flanged marginal portion of the top 4 as shown. A metal casing or housing 5 is positioned between the top and bottom portions and is seated in grooves formed in such portions. The cover, top and bottomportions are held together by means of a pair of front tie rods 10 and a rear tie rod ii.

It will be seen that the construction provides a relatively large housed portion between the base i and the top 4 within which substantially all of the operating mechanism is positioned and that the space between the cover 8 and the top 4 provides a housed spaced within which the thermostatic members or condition responsive means is positioned.

The circuit breaker chosen for illustration is a two pole circuit breaker provided with a pair of stationary contacts 12 which are connected to the line terminals 13. The movable contacts are indicated at i4 and are in the form of plug-shaped members secured to rigid arms 15, see Figure 1. The movable contacts are each carried by a channel-shaped metal member is and are freely slidable through the rear wall of such member. Each movable contact 14 is urged outwardly by a spring 11. The metal channel-shaped members I! loosely house the rigid arms 15. The metal channel members it are rigidly secured to a rock shaft indicated generally at II. This rock shaft, as shown most clearly in Figure 3, is provided with a rectangular metal center member is which is encased in a rectangular insulating sheath 20. The rigid arms I5 are connected to flexible leads or conductors 21 which extend upwardly on opposite sides of the device and are connected to connecting portions 22 in turn electrically connected to the right and left-hand pair of thermostatic members, as may be seen from Figures 1 and 8.

Each pair of thermostatic means comprises an outer thermostatic member 23 adapted to control a light switch and an inner thermostatic member 24 adapted to control the circuit breaker. These thermostatic members are bimetal members and will be described in greater detail hereinaften The thermostatic members 23 and 24 are individually anchored at their rear ends and adjacent their free ends are electrically joined by means of flexible connectors 25 to the load terminals 28, see Figure 8. This permits independent mechanical motion of the thermostatic members 23 and 24 although such members are electrically connected. The purpose of this will appear hereinafter.

Switch operating means in the form of a channel-shaped metal member 21 is rigidly secured to the shaft ll, as shown in Figures 3, 6 and '7. The switch operating means 21 is provided with elongated, longitudinally extending slots 28 in its side walls within which flanged rollers 29 are adapted to travel. The rollers 23 are carried by a transverse shaft 33. The shaft 30 is carried by an actuator formed of a pair of members 3| which are pivoted as indicated at 32 to a rigid channel-shaped frame 33. The frame 33 is carried by the transverse web 1. The rollers 29 and the shaft 33 constitute the first pivot means and are adapted to rock the switch to open and closed position when the actuator is rocked about the pivot pins 32 in a manner hereinafter to appear.

The upper end of the switch operating means 21 has spaced arms which are provided with a second pivot means which consists of shafts 34 upon which rollers 35 are mounted, see Figures 1, 4 and 7. The rollers 38 are adapted to travel in arcuate slots 35 formed in the rigid frame 33 and the shaft and rollers constitute the second pivot means for the switch operating member 21. Normally the second pivot means is held locked in its outermost position, that is to say, adjacent the righthand end of the slot 36 as viewed in Figure 1, by means of the main latch lever 31. This latch lever is provided with a pair of arms located on opposite sides of the rigid frame 33 and pivoted as indicated at 33 to such frame. The arms are joined by means of a transverse web 39 provided with cut out portions 43, see Figure 4.

Biasing means are provided which bias the second pivot means 34, 33 to the left as viewed in Figures 4 and '7. This biasing means consists of a compression spring 4| which bears at 0pposite ends against U-shaped bail like members 42 and 43. The ball like member 42 is loosely pivoted on the pins and the bail like member 43 is loosely pivoted on the pins 34. A flat bar 44 extends loosely through the spring 4| and through the bail member 43 and is secured to the bail member 42. However, as stated the second pivot means 34, 35 is prevented from moving to the left under normal conditions by means of the latch lever 31. Each of the arms of the latch lever is provided with a downwardly projecting portion 45, see Figure 1, which is pro vided with a face 48 which has a slight slant, as may be seen from Figure 1 so that it acts like a cam and tends to bias the latch lever 31 towards clockwise or unlatching motion. It is also to be noted that the latch lever, due to the fact that its right-hand portion is heavier than its left-hand portion, is also biased toward clockwise motion by means of gravity.

The latch lever is normally prevented from moving to releasing position by means of a latch bar 41 pivoted intermediate its ends by means of the headed screw member 48 to the web 39 of the latch lever, as shown most clearly in Figure 2. The latch bar 41 is provided with a pair of outwardly projecting end portions 49 which are engaged by downwardly projecting fingers 58 of a spring loosely coiled about the member 48.

The parts are so arranged, as may be seen from Figures 2, 3 and 4, that the fingers 50 bear against the front face of the web 39 of the main latch lever and thus normally hold the latch bar 41 in a definite predetermined position transversely of the main latch lever 31. Auxiliary latch members 52 are loosely mounted on a pivot pin 53 and are preferably rigid with sleeves 53, see Figure 2, to provide adequate bearing surface on the pin. The auxiliary latch members 52 are provided with fiat faces 54 which normally engage beneath the projecting portions 49 of the latch bar, see Figure 3. These auxiliary latches or latch members 52 are urged in a counterclockwise direction by means of springs 55. They are normally prevented from rotation by means of shouldered portions 56 formed thereon and respectively engaging circular pads or members 51 rigid with threaded stems 58, which stems are threaded through insulating blocks 59 rigidly carried by the outer or free ends of the inner thermostatic members 24. Adjusting knobs 68 are carried by each of the threaded stems 58 but are not threaded thereon. Nuts GI and washers 62 are also carried by the threaded stems 58 and springs 63 bear against the nuts and against washers 64 which in turn rest upon fittings 65 carried by the insulating blocks 59, see Figure 3. The fittings B5 are each provided with an upturned finger 65 which is adapted to be engaged by the upturned finger 61 to thereby limit the extent of rotation of the adjusting knob 58.

It is to be noted that bimetal thermostatic members vary due to differences in material and in the process followed in their manufacture. Wide variations are taken care of by properly adjusting the threaded stems 58, it being noted that the upper end of the stems are slotted to receive a screw driver. After proper adjustment has been obtained, the knobs 60 are soldered or otherwise secured to the threaded shanks 58. Thereafter a certain range of adjustment is permitted as the knobs 60 may be rotated approximately 9. full revolution. In other words, the range through which the thermostatic members are to work is determined by the rough adjustment of the stems 58 in the insulating members 59 by means of a screw driver, as previously described, and within this range the exact adjust ment at which the thermostatic members are adapted to release the trip means is determined by the adjustment of the knobs E8.

The pins 53 may be carried by upturned arms 89 integral with a plate 69 secured to the top portion 4. The plate 69 is provided with projecting fingers 18 which are adapted to be engaged by the extensions ll of the auxiliary latches 82 to thus limit their counterclockwise motion. It is to be noted that each of the auxiliary latches 52 is provided with a cam like extension or finger 12. The purpose of these fingers 12 will be apparent when the operation of one of the thermostatic members 24 is considered. Suppose, for example, that one of the thermostatic members 24 operates and releases its auxiliary latch 52. This latch will execute a counterclockwise motion and in so doing the fingers 12 will strike the corresponding finger 49 of the latch bar and will rock the latch bar and cause disengagement of the other end of the latch bar from the other auxiliary latch 52, thus releasing the main latch lever 31. If both thermostatic members 24 release their auxiliary latches 52 simultaneously, it will be seen that both auxiliary latches move away from the transverse 1y extending latch bar and disengage the respective ends 49 thereof and allow the main latch lever 31 to move to releasing position.

The automatic release on overload is apparent from the above described structure. For example, when one or both of the thermostatic members or condition responsive members 24 releases its corresponding auxiliary latch lever 52, the main latch lever 31 will rock in a clockwise direction due to the fact that it is biased by gravity towards I this motion as its right-hand end is considerably longer than its left-hand end. However, it is more heavily biased towards this releasing motion due to the fact that the latching face 46, see Figure 1, is inreality a cam face and the pressure of the second pivot means 34, 35 against such face tends to cause clockwise or releasing rocking motion of the main'latch lever 31. When the main latch lever 31 releases the second pivot means 34, 35, the switch operating means 21 pivots about the first pivot means 29, 38 as it is biased towards counterclockwise motion by means of the spring 4! and the switch operating means and movable contacts l4 move from the position shown in Figures 1 and 3 to the position shown in Figure 7.

Main operating means are provided for operating the switch and for resetting the automatic tripping means. This main operating means comprises a U-shaped, bail like member 13 which is pivoted as indicated at 14 on opposite sides of the stationary frame 33. The main operating member 13 may be rocked from the position shown in Figures 1 and 3 to that shown in Figure 6 in any suitable manner, as by means of connecting links 15 pivotally connected by means of a transverse pin 16 with the main operating means 13 at their outer ends and at their inner ends pivoted to a crank 11 rigidly mounted on a transverse rock shaft 18 carried in suitable supports and extending laterally through one side of the housing '9 as shown in Figure 5.

The rock shaft 18 may be operated in any suitable manner as by means of a handle 19 located externally of a transformer casing 80, the circuit breaker being preferably carried by the transformer indicated generally by the reference character 8| and mounted below the level 82 of the oil within the casing, see Figure 9. Obviously the rock shaft 18 could be operated in any other manner desired, as by means of cranks and link mechanism from a rock shaft mounted above the oil level if desired. If the outwardly projecting extension 83 of the rock shaft is below the oil level 82, a suitable packing is provided to prevent loss of oil.

The main operating means 13 is connected by meas es means of a pair of springs 94 with the first pivot means 29, 99. Preferably fittings 99 and 99 are providedfor the outer ends of the springs 94. These fittings are seated within grooves formed in the pins or shafts l9 and 99, see Figure 3. The

fitting 99 is mounted between the flanged rollers 29. It is also preferable to provide collars 99 on the shaft I9 to prevent shifting of such main operating shaft.

The main operating member 19 is provided with pins 99 which project inwardly from opposite sides and which are adapted to operate within slots 99 formed in opposite sides of the frame 93. These pins project into cut out portions 9I in the actuator formed of the members II. It is to be noted that the cut out portions 9| in the actuators 9| are so shaped that shoulders 92 are provided, see Figure 3. The purposeof these shoulders will appear from the following description of the manual operation of the apparatus.

Assume that the circuit breaker is in closed position and it is desired to manually open it. This is accomplished by rocking the rock shaft 19 and thereby moving the main operating means 13 from the position shown in Figures 1 and 3 to the position shown in Figure 6. During this rocking motion the line of pull of the springs 94 will pass across the pivot means 92 of the actuator composed of the members 9i and will cause the actuator to suddenly rock in a clockwise direction to the position shown in Figure 6, thereby suddenly opening the circuit breaker. Obviously closing motion is-accomplished by moving the main operating means from the position shown in Figure 6 to the position shown in Figure 3, the closing motion of the circuit breaker being very quick in view of the fact that the line of pull of the springs again crosses the pivot 92 of the actuator in passing from the position shown in Figure 6 to that shown in Figure 3. The shoulders 92 on the members 9| constituting the actuator, see Figure 3, have a double function. One of the functions is to start motion of the actuator at approximately the instant that the line of pull of the springs 94 is crossing the pivot point of the actuator when the main operating means 19 is being moved from the position shown in Figure 3 to that shown in Figure 6. The other purpose of the shoulders 92 is to insure opening of the circuit breaker by positive engagement between the pins 99 and the shoulders 92 even through the springs 94 should break, thus providing this additional safety feature.

The resetting after automatic tripping is accomplished by moving the main operating means 12 from the position shown in Figure 7 to the position shown in Figure 6. Prior to the time that the main operating means 13 arrives at the position shown in Figure 6, it will be noted that the line of pull of the springs 94 passes across the pivot point of the actuator and consequently pulls the upper end of the switch operating means 21 to the right as viewed in Figure 6, thus compressing the spring H as the springs 94 exert a greater force than the spring 4 I. It is to be noted that the projecting portion 3 which extends upwardly from the base I is engaged by the transverse insulated shaft I9 of the switch operating means 21 during this resetting operation and consequently the switch operating means 21 pivots about the point of engagement between the shaft I8 and the projection 3. As the main operating means 13 continues upwardly to the position shown in Figure 6, it will engage the downwardly projecting portions 99 of the main latch lever 91 and will rock such main latch lever to the position shown in Figure 6, the second pivot means 94, 99 having been first positioned to the right of the hook-shaped left-hand end of the main latching lever 91.

It is to be noted also that the auxiliary latches 92 are also reset. If both of the auxiliary latch levers 92 have been released by simultaneous action of the thermostatic members 24, it will be noted that the latch bar 41 will move upwardly and will simultaneously engage the cam portions 12 of each of the auxiliary latch levers l2 and will rock such latch levers to the position shown in Figure 6. During this motion, assuming that the thermostatic members 24 have cooled, the cam like portion 94 of the auxiliary levers will ride beneath the stops or pads 91 and will slightly raise the pads until the latching faces I of the auxiliary latch levers 92 are to the right as viewed in Figure 6 of the members 51. Thereafter when the main operating means 19 is moved downwardly towards closed position from the position shown in Figure 6, the transverse latch bar will rest upon the fiat portions or book portions 94 of the auxiliary latch levers 52.

If only one of the thermostatic members 24 had operated, its auxiliary latch lever 92 would be released but the other latch lever would still be held by its thermostatic member 24. Under these conditions when the main latch lever 31 is rocked from the position shown in Figure '7 to that shown in Figure 6 during resetting, the appropriate end 49 of the latch bar will first engage the cam portion 12 of the released auxiliary latch lever 92 and its opposite end 49 will be rocked inwardly and will thus clear the hook portion of the unreleased auxiliary latch member 92. Continued upward motion of the latch lever 91 will cause the latch bar 41 to reset the released auxiliary latch lever 92 as the cam portion 12 of the unreleased auxiliary latch lever 52 will rock the latch bar 41 by engaging one end 49 thereof and cause the other end 49 to rock inwardly and reset the released auxiliary latch lever 52.

A pair of signal switch members are provided and are connected together. Each signal switch member comprises a stationary contact member and a movable contact member 99 normally spring urged towards open position as shown in Figure 1. These signal switches are connected in parallel as is obvious and in series with a signal lamp or other signal means indicated by the reference character 91 in Figures 9 and 12. This signal lamp may be supplied from either secondary winding 99 of the transformer 99, see Figure 12, or may be, in the preferred form, supplied from a separate secondary I99 of the transformer 99. The signal switch means are controlled by the outer thermostatic member 23, see Figures 1 and 8. These thermostatic members are provided with insulating blocks I9I at their free ends through which threaded stems I92 pass. These stems are provided with pads or stop members I93 and with adjusting knobs I94 of identically the same construction as those previously described and initially set and subsequently accurately adjusted in exactly the same manner as that previously described.

Each thermostatic member 29 controls a signal switch operating means I95 which is mounted opposite the movable contact 96 of the signal switch and which is urged by means of a spring I99 in a counterclockwise direction towards signal switch closing motion.

of the signal switch operating means I05 with the stop or pad I03 of the thermostatic member. When the thermostatic member releases the signal switch operating means I05, such signal switch operating means closes its signal switch. The signal switch operating means I05 is provided with a cam face I08 so that the cam face will ride beneath and raise the pad or stop I03 when the signal switch operating means I05 is reset.

Each signal switch operating means I05 is pivotally mounted upon a fixedly positioned pin I08 carried by the stationary arms of a bracket H secured to the top 4. Preferably sleeves I09 have their ends riveted to the members I to provide extensive bearing surfaces on the pins I09. The signal switch operating means I05 are provided with projecting pins I II which are adapted to be engaged by the upper ends of resetting levers I I2 pivotally supported on the shaft 3 which in turn is supported from the base I, see Figures 1 and 2. Preferably tubular members or sleeves I I4 are riveted as indicated at 5 to the resetting levers II! so as to provide the resetting levers with elongated bearings which are supported by the shaft I I3.

The levers II2 are provided with cam portions H6 adapted to be engaged by the transverse pin 16 of the main operating means 13 when such main operating means is rocked upwardly. The cam portions IIE of the resetting levers H2 are so positioned that resetting takes place when the main operating means 13 is moved towards switch open position but prior to the opening of the circuit breaker so that it is possible, if it becomes desirable, to open the signal switch means by esetting the signal switch operating means without opening the circuit breaker.

The adjustment of the threaded stems 58 and I02, see Figures 1 and 3, which are supported from the thermostatic members 24 and 23 respectively, is such that any desired spread between current values required to operate the respective thermostatic members may be obtained so that the signal switch means will be closed for a current value and time interval less than that for which the circuit breaker will be opened.

The circuit breaker may be adapted for wall mounting as indicated in Figure 11 and may be completely housed as indicated at 9' and may be provided with an external lever or arm I9 for operating such circuit breaker. The signal. lamp or other signal means, not shown in Figure 11, may be mounted either on the casing of the circuit breaker or at any desired point.

Referring to the wiring diagram of Figure 12, it will be seen that the primary of the transformer is indicated by the reference character II! and that the secondary has a grounded neutral in the particular form chosen for illustration. It is obvious that either a single pole circuit breaker could be used where a single secondary is employed or a two pole circuit breaker could be used for the three wire grounded neutral system shown in Figure 12, or any number of poles could be provided by suitably extending the shaft l8, see Figure and providing it with the necessary number of movable contacts I 4 and providing a corresponding number of stationary contacts I2.

It will be seen that a novel form of circuit breaker has been provided which is so made that it may be mounted in the casing of a transformer or other instrumentality and is arranged It is normally rei strained by the engagement of the shoulder I0 1 to give an indication of an overload and which is also arranged to open the circuit in the event the overload reaches a predetermined value. The invention is particularly useful in that it will indicate an overload of any predetermined magnitude which may be of a lesser value, for example, than that required to open the circuit breaker but which nevertheless may be of such a value as to cause undue heating of the transformer. It is obvious, therefore, that the indicating means may be set to respond to an overload of a predetermined value and the circuit breaker opening means may be set to respond to an overload of a greater value and any desired spread or difference in current values for these two operations may be obtained by appropriate adjustment of the device.

It is to be noted further that when the signal switch means is once closed, it remains closed until manually opened, as described hereinabove. Inthis manner an indication is given of the fact that the transformer either is continuously overloaded or has been overloaded at some period between inspections. Thus the lineman is apprised of the condition of the transformer by a casual inspection thereof without requiring any elaborate tests. It is therefore possible to determine whether the transformer is adequate for the load normally carried thereby and also possible to determine whether the peak load at any particular time in the day exceeds the rated capacity of the transformer by suitably timing the inspection of the signal light. For instance, if it is believed that an overload occurs only between certain hours, it is possible by attempting to reset the signal means and observing it during these hours and at other times to determine just when the overload occurs. It is obvious that if the overload still persists at the time an attempt is made to reset the signal means, that the thermostatic member or members controlling the signal light will be in a position to prevent resetting as they will be out of position to hold the signal light controlling means in signal switch open position. On the other hand, if the overload has ceased at the time it is attempted to reset the signal means, the signal means will of course remain in non-signalling position when the signal means is reset. The ability to reset the signal means without opening the circuit breaker is a material asset for the apparatus as it enables tests of the above described type to be conducted without disturbing the service to the customers.

In this connection it is to be noted particularly that separate and independent condition responsive means, such as the bimetallic thermostatic members, are provided for respectively controlling the signal means and the circuit breaker release or opening means and that these two instrumentalities may be independently adjusted in a very easy and simple manner, each condition responsive means being wholly independent in its action from the other.

It is to be noted further that the adjustment of the thermostatic release means is very accurate and the exact value at which each thermostatid means will respond can be accurately predetermined by the adjustment of the adjusting knobs. If desired, it is obvious that scales, not shown, could be provided to indicate the values of current at which the respective thermostatic members will respond. By having the thermostatic members controlling the signal means and the circuit breaker wholly distinct and sepameans load responsive means or thermostatic means 2| in conjunction with the main switch means protects the second overload responsive means or thermostatic means 23 by opening the circuit if the overload exceeds a predetermined value. This is very desirable as the second overload means or thermostatic means 23 responds to a lesser overload and would become injured on very much larger overloads unless the main or first overload responsive means or thermostatic means would cause the main switch to open.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

l. A circuit breaker formed as a unitary structure and comprising switch means, switch operating means for opening and closing said switch means, main operating means for operating said switch operating means, biased means for moving said switch operating means towards switch open position, a first condition responsive means normally restraining said biased means and re-- leasing said biased means upon the occurrence of a predetermined condition, a second condition responsive means distinct and separate from said first condition responsive means and operable independently of said first mentioned condition responsive means, said second condition responsive means being responsive to a condition of lesser magnitude than said first condition responsive means, signal means controlled from said second condition responsive means and actuated upon the occurrence of a second predetermined condition, said signal means normally occupying a non-signalling position and being'movable upon the occurrence of said second condition to a signalling position, and means actuated from said main operating means for restoring said second means to its non-signalling position.

2. A circuit breaker comprising switch means,

switch operating means for opening and closing said switch means, main operating means for operating said switch operating means, biased means for moving said switch operating means towards switch open position, a first condition responsive means normally restraining said biased means and releasing said biased means upon the occurrence of a predetermined condition, a second condition responsive means, said second condition responsive means being responsive to a condition of lesser magnitude than said first condition responsive means, signal means normally occupying a non-signalling position and controlled from said second condition responsive means and movable to a signalling position uponthe occurrence of a second predetermined condition, said signal means remaining in signalling position, and means actuated from said main operating means for restoring said signal means to its non-signalling position.

3. A circuit breaker comprising switch means,

12 switch operating means for opening and closing said switch means, main operating means for operating said switch operating means, biased means for moving said switch operating means towards switch open position, a first condition responsive means normally restraining said biased means and releasing said biased means upon the occurrence of a predetermined condition, a second condition responsive means, said second condition responsive means being responsive to a condition of lesser magnitude than said first condition responsive means, signal means normally occupying a non-signalling position and controlled from said second condition responsive means and movable to a signalling position upon the occurrence of a second predetermined condition, said signal means remaining in signalling position, and means actuated from said main operating means for restoring said signal means to its non-signalling position when said main operating means is moved towards switch opening position.

4. A circuit breaker comprising switch means, switch operating means for opening and closing said switch means, main operating means for operating said switch operating means, biased means for moving said switch operating means towards switch open position, a first condition responsive means normally restraining said biased means and releasing said biased means upon the occurrence of a predetermined condition, a second condition responsive means, said second condition responsive means being responsive to a condition of lesser magnitude than said first condition responsive means, said first and second condition responsive means being adjustable each independently of the other, normally open signal switch means, signal switch operat-, ing means for closing said signal switch means and biased towards signal switch closing motion and normally restrained by said second condition responsive means and released upon the occurrence of a second predetermined condition, and means actuated from said main operating means for restoring said signal switch operating means to signal switch open position.

5. A circuit breaker comprising switch means, switch operating means for opening and closing said switch means, main operating means for operating said switch operating means to open said switch means when said main operating means is moved in one direction and to close said switch means when said main operating means is moved in the other direction, biased means for moving said switch operating means towards switch open position, a first condition responsive means normally restraining said biased means and releasing said biased means upon the occurrence of a predetermined condition, a second condition responsive means, said second condition responsive means being responsive to a condition of lesser magnitude than said first condition responsive means, said first and second condition responsive means being adjustable each independently of the other, a normally open signal switch, signal switch operating means biased towards signal switch closed position and normally restrained by said second condition responsive means and released upon the occurrence of a second predetermined condition, and means for restoring said signal switch operating means to its initial position when said main operating means is moved part way towards switch open position, whereby said signal switch means may be opened without opening said switch means 6. A circuit breaker comprising main switch means, main operating means including manually operable means for moving said main switch means to open and closed position, signal switch means, a first overload means responsive to a predetermined overload to cause closing of said signal switch means, means operated from said main operating means for moving said signal switch means to open position, and a second overload means distinct and separate from said first overload means and responsive to a diiferent predetermined overload to cause opening of said main switch means, said first and second overload means being electrically connected and independently mechanically movable.

7. In a circuit breaker constructed as a unitary device and having main switch means, a signal switch means, a pair of biased elements for respectively causing opening of said main switch means and closing of said signal switch means, main operating means including manually operable means for moving said main switch means to open and closed position, signal switch means to open and closed position, signal switch means, a first thermostatic means responsive to an electrical overload to cause closing of said signal switch means, means operated from said main operating means for moving said signal switch means to open position, and a second thermostatic means responsive to an electrical overload of a larger value than said first mentioned overload for causing opening of said main switch means, said first and second thermostatic means being electrically connected in parallel and being independently mechanically movable.

10. A circuit breaker comprising main switch means, main operating means including manually operable means for moving said main switch means to open and closed position, signal switch means, a first thermostatic means responsive to an electrical overload to cause closing of said signal switch means, means operated from said main operating means for moving said signal switch means to open position, and a second thermostatic means responsive to an electrical overload of a larger value than said first mentioned overload for causing opening of said main switch means, said first and second thermostatic means being electrically connected and being independently mechanically movable, said first and second thermostatic means having independently adjustable means to selectively determine the overload at which said signal switch means will close and the overload at which said main switch means will open.

ALWIN G. STEINMAYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 827,698 Adams Aug. '7, 1906 1,128,081 Vogel Feb. 9, 1915 2,223,531 Putnam Dec. 3, 1940 

